Electrolytic marking of metal objects

ABSTRACT

THE INVENTION IS CONCERNED WITH ELECTRLYTICALLY MARKING THE SURFACE OF METAL OBJECTS. APPARATUS FOR CARRYING OUT THE INVENTION INCLUDES AN ELECTRODE HAVING AN OPERATIVE FACE BEARING MARKINGS WITH WHICH IT IS DESIRED TO MARK SAID SURFACE. FLOODING MEANS IS PROVIDED FOR FLOODING THE SURFACE WITH ELECTROLYTE. AND MEANS ARE PROVIDED FOR APPLYING ELECTRIC CURRENT TO SUSTAIN ELECTROLYTIC ACTION.

Feb. 9, 1971 A. E. GODBEHERE ELECTROLYTIC MARKING OF METAL OBJECTS Filed April 8, 1968 FIG. 2

FIG.

fla /W 8 A'LEEET EDWARD GODBEHEEE United States Patent 3,562,132 ELECTROLYTIC MARKING 0F METAL OBJECTS Albert Edward Godbehere, Shefiield, England, assignor to Edward Pryor Development Limited, Sheffield, England, a company of Great Britain, and Northern Ireland Filed Apr. 8, 1968, Ser. No. 719,543 Int. Cl. B01k 3/04; C23b 5/72 US. Cl. 204-224 5 Claims ABSTRACT OF THE DISCLOSURE The invention is concerned with electrolytically marking the surface of metal objects. Apparatus for carrying out the invention includes an electrode having an operative face bearing markings with which it is desired to mark said surface. Flooding means is provided for flooding the surface with electrolyte. And means are provided for applying electric current to sustain electrolytic action.

The invention relates to the electrolytic marking of metal objects, and has for its object to provide an improvement therein.

According to one aspect of the invention, a method of electrolytically marking metal objects comprises the steps of flooding the surface to be marked with an electrolyte and bringing an electrode member into close proximity with said surface, the electrode member bearing either in relief or in intaglio the letters, figures or other markings with which it is required to mark said surface, the electrode and the object to be marked being connected into an electric circuit suitable to cause an electrolytic action to occur between the two. Preferably, the surface to be marked is flooded with the electrolyte by means of a'jet or a series of jets extending through the electrode assembly and so positioned that electrolyte is ducted onto the surface to be marked.

According to a further aspect of the invention, an electrode for carrying out the method includes at least one duct extending therethrough for the flow of electrolyte to the face of the electrode. The electrode is preferably contained within or provided with an outer covering of an insulating material (e.g. an epoxy resin) and the duct for the flow of electrolyte to the face of the electrode is preferably formed in said material.

In order that the invention may be fully understood and readily carried into effect, a preferred embodiment thereof will now be described, by way of example only, with reference to the accompanying drawings, of which:

FIG. 1 is a semi-diagrammatic view of an arrangement embodying the invention,

FIG. 2 is a sectional view of an electrode embodying the invention, and

FIG. 3 is an enlarged sectional view through the face of the electrode shown in FIG. 2.

Referring now to FIG. 1 of the drawings, an unpper surface of a metallic object 12 which it is required to mark by an electrolytic process is made the anode and is flooded with an electrolyte directed onto said surface from a nozzle 14. An electrode 16, bearing in relief on its underside the letters, figures, or other markings with which it is required to mark said surface, is mounted in such a 3,562,132 Patented Feb. 9, 1971 manner beneath a movable structure (not shown) that it can be lowered into close proximity with the surface to be marked. Non-conducting elements 18 are provided to limit the downward movement of said die so that an electrolytic action can occur between the die and the object to be marked, said die and said object being connected into a suitable electric circuit.

During the time in which the electrolytic action takes place (which incidentally can be varied from A sec. to 20 secs. according to the depth of mark desired), the current flowing may be in the region of amps per square inch. By varying the applied voltage between 0 and 20 volts the current is controlled to produce the quality of mark and depth of mark desired.

Referring now to FIGS. 2 and 3 of the drawings, an electrode for carrying out the method just described includes a metallic body part 20 bearing in relief at its face (that is to say on its underside) the letters, figures or other markings 22 with which it is required to mark a surface. Said body part is encased in a block 24 of epoxy resin insulating material into which extends a main flow passage 26 for an electrolyte. A plurality of flow passages 28 extend between said main flow passage and the face of the electrode so that the electrolyte can be directed as a plurality of jets just where it is required.

The insulating material may have been cast in a mould around the body part whilst the latter has rested upon the markings 22 placed in the base of the mould. In the finished electrode, therefore, the face of the electrode lies flush with the exposed ends of the markings. It is convenient, therefore, to hold the face of the electrode clear of the surface to be marked by strips of adhesive tape 30 stuck to the insulating material at points flanking the markings. The tape will be a few thousandths of an inch thick, that is to say the required thickness of the gap between the face of the electrode and the surface to be marked.

It has been found that marking a metal article by a method embodying the invention has resulted in a mark of greater depth than has previously been obtained using existing electrolytic marking processes. It also avoids the use of fragile stencils.

Various modifications may be made to the apparatus for carrying out the invention. For example, the elements 18 or the strips of adhesive tape 30 could be omitted and the die moved down to an adjusted position by means of a servo mechanism.

Round workpieces can be marked by having a suitably concave electrode and similarly other shapes can be marked.

What I claim and desire to secure by Letters Patent is:

1. Apparatus for electrolytically marking the surface of a metal object comprising: a metallic electrode having an operative face bearing metallic markings in relief, said raised metallic markings constituting the sole means corresponding to the mark to be made on said surface, flooding means for flooding said surface with electrolyte and means for applying electric current to said object and to said electrode suitable to sustain electrolytic action be tween said raised metallic markings and said surface to be marked.

2. Apparatus as claimed in claim 1 wherein said flooding means comprise at least one duct extending through the electrode having a size and being positioned to be able to flood said surface with electrolyte.

3. Apparatus as claimed in claim 1 wherein said electrode is fast with an insulating material and said flooding means comprise at least one duct extending through said insulating material having a size and being positioned to be able to flood said surface with electrolyte.

4. Apparatus as claimed in claim 3 wherein said electrode is mounted within said insulating material.

5. Apparatus as claimed in claim 4 wherein said flooding means comprise a plurality of ducts extending through said insulating material and through said electrode and being of a size and positioned to be able to flood said surface with electrolyte.

References Cited UNITED STATES PATENTS 10 JOHN H. MACK, Primary Examiner D. R. VALENTINE, Assistant Examiner US. Cl. X.R. 

